There has been widely used a storage system including a plurality of high-capacity storage devices, such as HDDs (Hard Disk Drives).
With the development of storage devices in scale and performance, the power consumption of each storage device has increased. This makes it more important to reduce the power consumption of the entire storage system. In view of this, for example, to optimize the configuration of a storage apparatus that uses a pool, there has been proposed a technique for providing the optimum configuration while ensuring policy, such as power saving performance or response performance, set by an administrator. Further, there has also been proposed a technique that realizes reduction of the power consumption, simplification of management, and enhancement of storage resource use efficiency.
Japanese Laid-open Patent Publication No. 2009-116436
Japanese Laid-open Patent Publication No. 2010-33261
When a ratio of a used storage area to a total storage area of an operating one of a plurality of storage devices exceeds a predetermined ratio, it sometimes occurs that an unused one of the plurality or storage devices is activated to increase the total storage capacity of the storage devices in operation. In doing this, if a storage device which consumes as low electric power as possible is put into operation, it is possible to reduce the power consumption of the whole system.
However, the above-mentioned method has a precondition that the storage devices having been in operation continue to be operated, and hence if a case is taken into consideration where any of the storage devices having been in operation is powered off, there is a possibility that the power consumption is further reduced.